Step #1. Clean the part to be painted, and then clean it again, and then clean it one more time.
In all seriousness, clean the daylights out of it, use acetone or prep-sol and wipe out all the grease and finger oils that get left in the corners and welds. If you don't have it spotless and grease free then it will lift in those areas later. I blow it dry with compressed air to get rid of any lint, but if you don't have access to a compressor you can pick up tack cloths for cheap at paint supply stores.
I primer with a couple of coats then I let the part sit for a few days. The primer will dry and shrink, and that will reveal any bad spots that need more primer or attention. If it looks good and doesn't need any more primer I'll scuff it with scotchbrite pads and blow it off again, wipe it down with prep-sol one last time, blow it dry and then paint.
The best way I've found to get the paint to flow good and stick is to shoot light coats, and let them get tacky in between coats. If you wait too long you get "dry" paint, which looks like paint over fuzz, and if you don't wait long enough you'll get too much wet paint built up and it will sag and run.
After I get the paint looking the way I want I set it somewhere out of the way so it won't get bumped or dirty, and if possible I set it upright so that if anything does sag or run it less likely to be on top where it will be harder to fix. I've never tried drying paint in the oven...the thought of my wife kicking my butt because I burned down the house is not appealing to me!